2.07 Remember the structures of the digestive system

What are the structures of the digestive system? Essential Question What are the structures of the digestive system? 2.07 Remember the structures of the digestive system

Structures of the digestive system Also known as: Alimentary Canal Digestive Tract Gastrointestinal Tract Upper GI Lower GI Approximately 30’ in length from mouth to anus 2.07 Remember the structures of the digestive system

Structures of the digestive system Primary structures Mouth Esophagus Stomach Small intestines Large intestines Accessory structures Tongue Teeth Salivary glands Pancreas Liver Gall bladder 2.07 Remember the structures of the digestive system

Structures of the digestive system Mouth (buccal cavity) Tongue Teeth Salivary Glands Palate Uvula 2.07 Remember the structures of the digestive system

Structures of the digestive system Tongue Attached to floor of mouth Made of skeletal muscle attached to four bones Taste buds on the surface Sweet Sour Bitter Salty 2.07 Remember the structures of the digestive system

Structures of the digestive system Teeth Primary (deciduous) 20 “baby teeth” Secondary (permanent) 32 “adult teeth” Did you know??? Canine teeth are also known as cuspids and eye teeth. 2.07 Remember the structures of the digestive system

Deciduous Teeth: baby’s first teeth which eventually fall out All deciduous teeth are in place by 2 ½ years. Between 6 and 12 years, deciduous teeth begin to fall out and are replaced by 32 larger permanent teeth TYPES OF TEETH Incisors: located at the front of the mouth, they are blade sharp and are used to cut food 2. Canine teeth: located next to incisors, used for holding, tearing or slashing food 3. Bicuspids, or premolars: crush and grind food 4. Molars: Located in the very back of the mouth, have flattened tops, crush and grind food. Structure of Teeth All teeth have a cow, neck and root Crown: The visible portion of the tooth covered by enamel (which is the hardest biologically manufactured substance) Neck is the transitional section that leads to the root Root: the portion of the tooth that anchors it to its bony socket. It’s held in place by fibers. MOST Teeth are made up of dentin, a mineralized bone like substance. Inside teeth there’s a layer of connective tissue called pulp located inside the pulp cavity. Pulp cavity contains blood vessels that provide nutrients to the tooth and nerves which provide sensation to the tooth. Gums hold your teeth in place.

Structures of the digestive system Salivary glands Parotid glands: located anterior and inferior to each ear. Swell when you get mumps Largest salivary gland Submandibular gland located along the inner surface of the lower jaw Sublingual gland Located under tongue 2.07 Remember the structures of the digestive system

Salivary glands produce 1-1.5 liters of saliva daily. Small amounts are continuously secreted to keep the mouth moist. Saliva is 99.4% water and contains antibodies, buffers, ions, waste products and enzymes Function of saliva: Contains enzymes that begin the chemical breakdown of food After eating, saliva cleans the oral surfaces, reducing the amount of bacteria that grow in the mouth

Structures of the digestive system Palate Hard Soft Uvula Flap of skin hanging in the back of the throat Aids in swallowing by directing food toward the pharnyx Uvula blocks food from entering your nose. 2.07 Remember the structures of the digestive system

Structures of the digestive system Pharynx (throat) Nasopharynx Connects to the nose Oropharynx Connects to the mouth Located at the back of the Tongue Laryngopharynx A passageway for food, Water, and air into the Internal parts of the body. ] 2.07 Remember the structures of the digestive system

Structures of the digestive system Esophagus Muscular tube, 10” long Transports food from the pharynx to the stomach Is a collapsed tube until a bolus of food is eaten. Esophageal wall layers Mucosa Submucosa Muscular External serous Rhythmic contractions called peristalsis push food down the esophagus. 2.07 Remember the structures of the digestive system

4 layers make up the alimentary tract Mucosa: innermost layer, lines the canal, contains cells that secrete enzymes to break down food, contains goblet cells that secrete mucus for lubrication Submucosa: the next layer Composed of soft connective tissue Contains blood vessels, lymph vessels, lymph nodes and nerve endings. Musculara Externa the next layer Innermost layer of muscle encircles the canal Outer most layer is longitudinal so it lies in the direction of the canal Serosa: the outermost layer makes up visceral peritoneum Peritoneum is a serous membrane in the abdominopelvic cavity. It has two layers: Visceral layer covers the organs and the parietal peritoneum lines the walls of theabdominopelvic cavity

At the end of the esophagus is a muscular “Door” called the lower esophageal sphincter . The LES is also known as the cardiac sphincter. It must open to allow food to move into the stomach After food passes through, it must close to prevent stomach acids from splashing back up into the esophagus. If the sphincter opens, it will cause heartburn (pyrosis)

Structures of the digestive system Stomach Upper left quadrant of the of the abdominal cavity Fundus Body Pylorus Cardiac Sphincter Pyloric Sphincter Rugae, The stomach is under the diaphragm and almost completely covered by the liver. It is approx. 10 inches long and can hold up to 4 liters of food when filled. Rugae are the folds in the stomach that help the stomach expand and contract. 2.07 Remember the structures of the digestive system

Serves as a temporary holding area for received food STOMACH FUNCTIONS: Serves as a temporary holding area for received food Secretes gastric acids and enzymes that mix with food, performing chemical digestion Regulates the rate partially digested food (chyme) enters the intestines Absorbs small amounts of water on a limited basis It takes about 4 hours for the stomach to empty following a meal. Liquids and CHO’s pass through quickly Proteins take more time Fats take the longest usually between 4-6 hours

Structures of the digestive system Accessories… Pancreas 6-9 inches long Located behind the stomach Extending from duodenum to the spleen It secretes buffers to neutralize the acids in the chyme saving the intestinal walls from damage Releases enzymes that break down sugars and starches, breaks down fats and proteins 2.07 Remember the structures of the digestive system

Gallbladder Sac shaped organ, 3-4 inches long Located under the liver’s right lobe It stores bile produced by the liver If the bile becomes over concentrated, bile salts may solidify forming gallstones Fatty foods in the duodenum (first section of small intestines) Cause the gallbladder to contract releasing bile into the common bile duct and this leads to the duodenum.

Liver Located in front of the diaphragm (anterior) Weighs 3.3pounds Is the largest glandular organ in the body Largest organ in the abdomen Is divided into a large right lobe and a smaller left lobe. Receives about 1 ½ quarts of blood every minute from the hepatic portal vein And hepatic artery. The blood provides oxygen rich blood that keeps the liver tissue alive

Destroys old blood cells and recycles their usable parts FUNCTIONS OF THE LIVER Creates body heat Detoxifies the body of harmful substances such as certain drugs and alcohols Destroys old blood cells and recycles their usable parts The pigment from bilirubin is a waste product and is eliminated in bile giving feces its distinctive color Forms blood plasma proteins such as albumin and globulins Produces clotting proteins: fibrinogen and prothrombin Manufactures bile, needed for the digestion of fats Stores and modifies fats for more efficient use by the body’s cells Synthesizes urea, a by product of protein metabolism, so it can be eliminated by the body Stores sugars (when our blood sugar levels fall below normal, the liver releases glucose into the blood stream Stores vitamins A, B12, D, E, and K Makes cholesterol

Structures of the digestive system Large intestines Approximately 2” in diameter 5’ long Begin at the junction of the ileum (last portion of small intestine) and extends to the anus 2.07 Remember the structures of the digestive system

Compaction of waste products for elimination Large Intestines are approximately 5 feet long and 25 inches in diameter FUNCTION Water absorption Absorption of vitamins produced by the health bacteria in the large intestine Compaction of waste products for elimination Large intestines contain no villi, so little nutrient absorption occurs here.

Three Main Regions of Large Intestines Cecum pouch shaped structure that receives any undigested food and water from the ileum The appendix is attached to the cecum The appendix is a 3 “ long, slender hollow, dead ended tube lined with lymphatic tissue The appendix has no current purpose If it becomes blocked or inflamed it causes appendicitis Colon has 4 secions: ascending colon, transverse colon, descending colon, and sigmoid colon(the S shape portion that extends from the left side to the rectum

Opens to the anal canal/anus RECTUM Opens to the anal canal/anus Anal sphincter opens and closes to allow the passage of solid waste(feces) from the colon to the outside world

What are the structures of the digestive system? Essential Question What are the structures of the digestive system? 2.07 Remember the structures of the digestive system